I need a Diagnosis...[shakes, stalls, sputters]

[AsILayDying]

Went to the tracks yesterday... ran a 15.136... drove the highway home and pushed my car the last few hundred feet home after it shook and stalled... clicking noise coming from the intake cam/valve region, hopefully not a rod. Car sputters when starting and engine shakes back and forth alot with a steady clicking every revolution. I don't want to run my car more than I have to cause I'm afraid something bad might happen, so I'm not driving it until I figure out what it is and fix it. I feel like an idiot, but i didn't catch this... a vaccuum hose going from a sensor to the fuel rail was unhooked for my third run ... I think this is quite possibly what caused the problem. It's the only explanation. I need advice... are these symptoms of a bent valve? or is the timing off? or did I bend a rod? I have no idea and I've been searching all day with hardly any luck...

 

[madman]

Hey,

I was looking at your car profile and noticed a couple things.

You are using a MBC, do you have a boost gauge and if so what boost were you running at on the track?

The higher the boost, you want a smaller gap on the spark plug and want to stick with a colder plug like the NGK's. I don't think that the Bosch Platinum Plugs are recommended for our cars, being turbo, I believe because the platinum plugs run too hot. Can anyone else second this?

If you are running a hotter spark plug and higher than stock boost, then that might have been part of the problem.

 

[ddavisaf]

The higher the boost the more supporting mods are required. It has nothing to do with the gap of your spark plugs. Our cars do not run well on platinum plugs. In fact, our cars run horrible on platinum plugs. The recommend plugs are NGK BPR 6ES gapped at .028". You will notice hesitation and stumbling while driving if using fouled, faulty, or wrong plugs. The vaccum line you're talking about runs to the fuel pressure regulator solenoid. Will that cause the problem you're experiencing? No. Just hook it back up and erase it as a possible cause. First thing first, change your spark plugs.

On to the "clicking" you're hearing. Make sure you have enough oil. Lack of oil will cause all sorts of problems and noises. The sound you are hearing may be the common noisey lifters DSMs are known for. Or it may be arcing between your coil packs. It could even be a power steering pump that's low on fluid. Try and pin point where the sound is coming from. Use a piece of vaccum line as a stethiscope (spell check would be nice for words like this) to help. Pay attention to whether the sound increases in speed and pitch when the rpms are manipulated. Let us know what you find out.

 

[madman]

The higher the boost the more supporting mods are required. It has nothing to do with the gap of your spark plugs.

I took this right from RRE website:

"Colder plugs will retain less heat between combustion cycles, thereby reducing the tendency toward damaging detonation elevated boost levels. Spark plug gap should be set at .030" for up to 16psi boost. Set at .028" for 17psi and up. "

http://roadraceengineering.com/eclignition.htm

 

[Defiant]

Sounds like timing belt.

 

[ddavisaf]

I took this right from RRE website:

"Colder plugs will retain less heat between combustion cycles, thereby reducing the tendency toward damaging detonation elevated boost levels. Spark plug gap should be set at .030" for up to 16psi boost. Set at .028" for 17psi and up. "

http://roadraceengineering.com/eclignition.htm

I understand that. You understand that. However, there may be others on the site that will read this and start thinking that by buying different spark plugs they can run more boost. That is all I'm trying to get across. I'm not saying you're wrong, I'm saying don't worry about turning up the boost until you have the supporting modifications to handle it (which includes colder spark plugs).
Great job on finding the reference. RRE has a ton of useful information on their site.

 

[slipstream808]

I feel like an idiot, but i didn't catch this... a vaccuum hose going from a sensor to the fuel rail was unhooked for my third run ... I think this is quite possibly what caused the problem.

What hose was it? The only thing I can think of (other than the fuel feed line and return line) is the air line for the fuel pressure regulator. Now if that came off, you might have some problems, with the car running too rich or too lean depending on whether you're in boost or not. The sensor it would have been hooked to would be the fuel pressure solenoid, and that only would be used when the car was starting, then the solenoid would open, allowing for the air leak.

 

[92awddsm]

What hose was it? The only thing I can think of (other than the fuel feed line and return line) is the air line for the fuel pressure regulator. Now if that came off, you might have some problems, with the car running too rich or too lean depending on whether you're in boost or not. The sensor it would have been hooked to would be the fuel pressure solenoid, and that only would be used when the car was starting, then the solenoid would open, allowing for the air leak.

Actually, the real problem with the vac line to the fpr is that if it breaks or come loose during boost, you are in trouble. We run a rising rate fpr which means, for every psi of boost, the fuel pressure increases 1 psi. Now, if you are running 20 psi of boost, your fp should be 57psi(1g) or 63psi(2g) at wot and at full boost. Without the boost reference line hooked up, you are running base fp(37psi on 1g, 43psi on 2g) under boost which causes a major lean condition. This in turn will melt spark plugs, burn pistons, burn valves or blow a hg or all at one time.

 

[nightspeed87]

Actually, the real problem with the vac line to the fpr is that if it breaks or come loose during boost, you are in trouble. We run a rising rate fpr which means, for every psi of boost, the fuel pressure increases 1 psi. Now, if you are running 20 psi of boost, your fp should be 57psi(1g) or 63psi(2g) at wot and at full boost. Without the boost reference line hooked up, you are running base fp(37psi on 1g, 43psi on 2g) under boost which causes a major lean condition. This in turn will melt spark plugs, burn pistons, burn valves or blow a hg or all at one time.

are we talking about the vacuum line for the boost gauge here? If so where do you recommend hooking it up, because I dont have a fuel pressure solenoid in my car at all ( but didnt mind too much because I live in FL ) because isnt it true that it helps with cold starts?

 

[92awddsm]

are we talking about the vacuum line for the boost gauge here? If so where do you recommend hooking it up, because I dont have a fuel pressure solenoid in my car at all ( but didnt mind too much because I live in FL ) because isnt it true that it helps with cold starts?

I am talking about the vacuum line that goes from the intake manifold to the fpr. If you had a fp solenoid, it would go from the intake to the solenoid and then to the fpr. If the line is broken, fp will not rise with boost.

 

[nightspeed87]

wait hold up... Ok i know what line your talking about from the manifold to the fpr, but your saying the fp doesnt raise with out the fp solenoid'? ( I heard the fp solenoid wasnt needed? )

And the other question im asking is , havent there been ppl who've tapped the boost gauge lines in there somewhere?
I just have mines going to the regular manifold line but recently read on vfaq that theres a better place to tap within the fpr lines?

 

[92awddsm]

wait hold up... Ok i know what line your talking about from the manifold to the fpr, but your saying the fp doesnt raise with out the fp solenoid'? ( I heard the fp solenoid wasnt needed? )

No, the fuel pressure rises with or without the solenoid as long as the vacuum lines are in place or not broken. Basically what Im saying is if the frp doesnt get reference from vaccum and, you a/fr will not be close to what it should. All the fp soleniod is there for is to richen the mixture for cold start up and other related situations.

 

[92awddsm]

And the other question im asking is , havent there been ppl who've tapped the boost gauge lines in there somewhere?
I just have mines going to the regular manifold line but recently read on vfaq that theres a better place to tap within the fpr lines?

The best place to tap the boost gauge is on a seperate port by itself anywhere on the intake manifold after the tb. You can tee into the fpr vac line but a seperate port would be better.

 

[brute]

Personally, All my ports are capped except for the "P" port. I use that for my boost gauge.

 

[slipstream808]

FP solenoid isn't needed. It's there for hot starts to shut off the feed of intake manifold pressure to the fuel pressure regulator. In your case it would set the FPR to keep the pressure at 37psi during a hot start. But other than that, it isn't used.

The solenoid allows air to go from the manifold to the fuel pressure regulator. When it is closed, there is no reference for the FPR so it runs at 37psi. It is always open unless it is a hot start. So again, it isn't needed.

Yes, you tap your boost gauge to the line between the FPS and the manifold. If you were to do it on the FPS to the FPR, you wouldn't see any readings on a hot startup.

Edit - Damnit 92awd, you beat me to it! HAHA!!

 

[AsILayDying]

Okay Okay... My friends and I popped off the valve cover today to check the cams. The cams appear to be fine, but in the process we discovered a couple of small shavings of metal right next to the valves above the 2nd piston from the left, but it was just 2 small pieces. My thought is that either one of the valves is bent/broken or the spring is messed up... I'm 90% sure that it has nothing to do with the pistons or rods. I'm thinking it might just be smartest to buy a rebuilt head from a good DSM site and swap heads..? Any opinions would be nice. I would like to mention that the previous owner lied to me about when he changed the oil because it is low and nearly black. It is foolish on my part for not changing it before I raced in the first place, but I was sure that it was somewhat new. Surprisingly, my dad is not very mad at all... so long as I understand that it's coming out of my pocket, which i do. As far as boost, I hooked it up to the stock solenoid a couple days before the race b/c I don't trust the Ebay part... it seemed very leaky when I was using it. And I never red lined at the tracks.

 

[DanThMan1983]

Get a compression tester from harbor freight(5-10 dollars). Pull all the spark plugs out. Pull the MPI fuse. Hook up the tester to a cylinder. Crank it over see what kind of reading you get write it down and do the same for the others. Post your results Whats the rule of thumb guys? shouldnt be more than 20% difference between cylinders?

 

[ddavisaf]

No more than 14psi difference between cylinders. Serive limit is 121psi on a 1G, 133psi on a 2G.

 

[AsILayDying]

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here's a video we made of the sound... u'll see my friend point to where it seems to be coming from.

soem guys on his mazda forum, msprotege.com, said it sounds like a snapped pin and bent rod, another said ti sounds like a lifter, and another said i needed to check my spark cause it sounded like it was otu a cylinder...

any thoughts?

 

[andymoraitis]

Sounds like a separated crank pulley beating itself to death on the lower cover or even a trashed balance shaft. Pull the driver side wheel and splash guard and have a look at the crank pulley. If that's not it, I would suspect rod knock which you can test for by pulling and replacing plugs one at a time. If the sound goes away when any one plug wire is removed and replaced, it's in the bottom end. If the noise continues with a plug wire pulled (make sure you test all four individually), it could be in the valve train. You might want to pull all of the lifters, bleed them down and make sure they compress smoothly. If they hang up in either the up or down position, they're collapsed and need to be replaced.

Keep us posted,

Andy

 

[AsILayDying]

Okay, My friend and I checked the plugs, and when we pulled the two on the left (individually), the noise continued and when we pulled the two on the right (individually) the car bogged down and almost died?!?!?! Is that normal cause the sound kept going as it was dying. It shouldn't be a rod or anything in the bottom end? right? let me know. For now, I think i'm gonna stick with replacing the valves and springs.

 

[andymoraitis]

If the sound continued while you were pulling plugs, I'd think it's safe to say you're out of the woods for bottom end trouble. To be sure, either remove the oil pan and look for shavings or drain the oil and drag a telescoping magnet in the pan.

Sounds more like a valvetrain issue though.

 

[92awddsm]

To me, it sounds as if it has spun a rod bearing bad enough that the piston is actually smacking the head when at tdc. I purchased a 93 tsi once that sounded indentical to that. The noise didnt stop when I pulled the plug wires so I decided to pull the head off. When I pulled the head, I immediately knew what the problem was after seeing the shiny area on the head and piston.

 

[AsILayDying]

I'm sorry, but the video is very misleading... the sound seems like it is coming from everywhere and when I listen to it, it isn't really a knocking... it's more of a clicking and it is right by the mid-left region of the intake cam. My friend posted it on his msprotege.com forum and alot of them had mixed opinions just like this thread, so i don't know who to listen to. After what I've heard, I'm 90% that it's somewhere in the valvetrain.

 

[andymoraitis]

You should still drop the pan and check for shavings. There's nothing quite like being absolutely sure before starting repairs that may be as extensive as this.